Researchers from several institutions in China, including Lanzhou University, Renmin University of China, and the Institute of Cultural Relics and Archaeology of the Xinjiang Uygur Autonomous Region, have published a groundbreaking study in the journal Science Advances, providing evidence that the systematic use of coal as fuel dates back to approximately 3,600 years ago. This discovery pushes back the history of early coal usage by approximately a millennium, expanding our understanding of human energy history and offering a new perspective on the human-environment relationship in prehistoric times.
The study, titled “Earliest Systematic Coal Exploitation for Fuel Extended to ~3600 B.P.,” was conducted through the collaboration of multiple researchers and institutes. While some prehistoric archaeological sites had shown sporadic combustion of coal for fuel, concrete evidence of prehistoric coal usage before 2,500 years ago had remained elusive until the archaeological excavations at the Jirentaigoukou (JRTGK) site in Nilka County, Ili Kazak Autonomous Prefecture, Xinjiang. The JRTGK site is a significant Bronze Age settlement.
The systematic excavations at JRTGK and its associated tombs, initiated in 2015, revealed indications of coal use along with evidence of copper production activities. Piles of coal, grey coal ash, partially burned coal, and coal residue in fire pits were discovered surrounding residential structures, suggesting intentional placement for easy access. Moreover, the coal carbon content at the site was relatively higher and more common than in some surrounding coal deposits, indicating an understanding of coal variations across different locations.
Subsequent excavations uncovered wooden carts at the site, which potentially sheds light on the transportation of coal in ancient times. These findings present a comprehensive evidence chain regarding coal fuel development, signifying that people had systematically developed and utilized coal fuel during that period.
Analyses of natural soil samples from the site and surrounding areas indicated significant enrichment of heavy metal elements in the late-stage layers, confirming the site’s role as a regional metallurgical center requiring substantial energy sources.
The researchers explained that the Ili region might have been influenced by a global climate deterioration event around 4,200 years ago, resulting in a decline in human activities between 4,200 and 3,800 years ago. The team speculated that the late-stage site experienced deteriorating vegetation, particularly a contraction in coniferous forests, due to a relatively colder climate. This decline, combined with an intensified demand for fuel from larger settlements and higher-intensity metallurgical activities, exacerbated societal-environmental conflicts, ultimately driving local communities to transition their energy sources.
The research on the JRTGK site is ongoing. In the future, researchers plan to explore whether there are concurrent or earlier/later instances of coal fuel usage in the surrounding regions. This exploration is highly significant for understanding the patterns of prehistoric societal evolution and exploring issues related to the spread and inheritance of prehistoric technologies. Additionally, researchers intend to investigate the environmental impact of substantial coal combustion to explore questions related to the Anthropocene epoch, primarily through the study of sediment around the site.
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